Category Archives: History

Space and physics news tends to consist of many, many small sparks of inspiration doing the rounds and dying down for a bit. So many, that occasionally, should a spark previously lost amid a sea of news activity re-emerge in times of lower headline flux, it can be mistaken for new news.

A few websites such as Discovery picked up on the story of new cleaned up footage of the early moments of Apollo 11, thought lost by NASA, but recorded by other stations. The reports state the footage has been painstakingly reassembled. All this is true, except for one minor problem – the footage was released during the 2009 celebrations of 40 years since the 1969 missions, as Universe Today noted.

Scientists at the European Planetary Science Congress 2010 have released a map of how the solar wind impacts differently on different parts of the lunar surface. Mapping how many solar wind protons are deflected by magnetic anomalies, the researchers found up to 20% of incoming solar wind particles were bounced away. Furthermore, maps of energetic hydrogen atoms created by the interaction of the 80% of solar wind protons that make it through and strike the ground show holes where the magnetic anomalies resisted the interactions. The size of the holes varies with the force of the solar wind, which blows with changing intensities, but the general outlook is one of areas of the lunar surface relatively protected from the ion flux and so less likely to be producing the minute amount of water that results from the interactions. Details here.

Someone who himself was once deflected on his way to the Moon is Jim Lovell of Apollo 13 fame (and previously Apollo 8, which orbitted but did not intend to land on the Moon). He discussed the future of spaceflight and other things over on Universe Today, the interview is here.

The space shuttle Discovery will be the next vehicle to have a final scheduled flight to the International Space Station. In preparation for November’s mission, the shuttle has already mounted launchpad 39A and been visited by photographers on the pad. The results are here.

I seem to be collecting these things today… sped up videos of various things to see in the sky.

First off, as the night draws in, a thin crescent Moon heads for the horizon in the west in this recent video:

Secondly, the Moon again, this time during the day as it passed in front of Venus as seen from some parts of the Earth. This daylight occultation was caught in South Africa in a series of images showing the crescent Venus reemerging from the body of the crescent Moon:

Deeper into the daytime and sundogs are making appearances either side of the Sun from a number of locations at the moment. Here’s a timelapse of one changing as the clouds blow through its area:

But of course, there are timelapse events happening in the world of research too, such as the latest image of supernova 1987A by Hubble, which has photographed the same supernova before. The reason? To see how such a thing modifies on the timescale of a human lifetime, giving some idea of the complexities involved in expanding nebulae and their interactions with external gas.

Of course sometimes it helps to vary sources of information to get even older data on an object with time. Researchers believe they have unearthed the oldest mention so far of Halley’s comet being visible in the skies. The observations, made by ancient Greeks in 466BC, predate the previous earliest accepted observation, by Chinese astronomers in 240BC, by three orbits. The Greeks write about a comet being visible in the west for around 75 days (simulations suggest up to 80 days of visibility of Halley’s comet, depending on atmospheric conditions, at this time) in the same year as a massive meteorite fell that then became a tourist attraction for half a millennia. The records, unlike the later Chinese ones, aren’t very detailed, and are second hand at best.

By which I don’t just mean our Moon, but various moons through the solar system, some of which have been in the spotlight.

Starting out at both Saturn and Earth – and the two are united in having Moons that are slowly shrinking as they cool, the effect being, as on Earth and more dramatically on Mercury, that the outer layer develops wrinkles, seen as mountain chains. Cassini made the discovery for Titan when mapping the icy world’s topography. Ripples of mountains, all orientated the same and clustered around the equator fitted a computer model of a small body, made of ice and rock with a subsurface ocean, slowly cooling over time as radioactive isotopes decay away. This causes the body to shrink, but the outer parts of the subsurface ocean to freeze and expand. Losing seven kilometres in radius and one percent of volume over the four billion or so years since formation, Titan has achieved two kilometre high mountains in its equatorial ranges. The features seen on our own Moon, by comparison, are much shorter – nine metres or so – but run on for kilometres and cover the whole surface. Equatorial ‘lobate scarps’ were first seen by the Apollo program, but only at the equator. More recent observations with the Lunar Reconnaissance Orbiter have identified further scarps dotted around the Moon. estimates of the shrinking of the Moon from the features suggests around 100m has been lost in around 800 million years, putting the Moon at a lower rate of radius loss than Titan. There is also the suggestion that instabilities in the contraction process are responsible for some of the Moon-quakes observed with Apollo hardware.

Titan wasn’t the only moon under the microscope of Cassini. During one flyby, the probe took images of three moons – Enceladus, Tethys and Dione. Images like this enable scientists to look at changing shadows on the surface of different moons that may help to eke out a little extra detail, or may even reveal a new area of the surface in unprecedented resolution at a given wavelength. They also help others to create computer models of moon surfaces for virtual flyby videos like these.

Of course, they’re also good just for being nice pictures. Stuart Atkinson has put up a post with one of the Enceladus pictures taken by Cassini, and another picture taken from the Mercury bound Messenger probe of a planet and a Moon. The planet happens to be Earth. Messenger wasn’t idly glancing into the void, however, the image was taken during a sweep for Vulcanoids – asteroids lying between the Earth and the Sun, unseen by terrestrial observatories due to the glare of our nearest star. These particular asteroids, should they exist, would be trapped in orbits that never take them as far out as ourselves, rather than actual asteroids or spent comets that have drifted inward. They shouldn’t exist, according to prevailing ideas on the formation of the solar system, so if just one is seen and later confirmed, it would be interesting. It would also mean that alongside the Oort Cloud, the Kuiper-Edgeworth Belt and the Asteroid Belt, we’d also have a Vulcanoid Belt, with new objects to study and slot into the history of the solar system.

For now, we’ll just have to study the solar system through the most ancient rocks available to present day geologists. The most recent block of ancient rock to be found has been dated at around 4.45 billion years old. The Earth is estimated to be 4.54 billion years old and so should the result be confirmed, the arctic rocks would date to a period before the crust of the Earth had formed, but after the core was created. The scientists measured the age looking at well known radioactive decay signatures, though others have suggested a better way would be to look for signatures from istopes believed to be around at the time, but which quickly decayed away in the earliest parts of terrestrial history.

The past and future evolution of planetary systems can have an impact on whether or not there are moons to be found. Hot Jupiter planets – gas giants that have migrated closer to their parent stars – are unlikely to have held onto their moons as they rode the gravitational turbulence further in and dealt with the gravitational forces from the closer proximity to their host star according to new research. Exomoon hunters (like David Kipping, quoted in the article) aren’t detered as the planets do still provide a testbed for observational techniques until our methods and instruments become capable of tackling extra solar planets with a higher likelihood of companion bodies.

Finally, the troubled evolution of Jupiter has been in the news (along with the evolution of its clouds, visible even in relatively small telescopes). The largest of our solar system’s planets has a small problem – its core is a little depleted compared to that of second largest planet Saturn. Current theory suggests that gas giants start out as a giant rocky/ice body, perhaps ten times the mass of the Earth, which then gravitationally hoovers up the gas surrounding it. The trouble is while Saturn shows evidence for the right size of core, Jupiter is a little lacking given its incredible overall mass. A new suggestion has been made that Jupiter’s own core has been in collision with four or five super-Earth’s, each skimming a bit off the top. It is hoped that the forthcoming Juno mission will be able to add observational evidence to the idea.

Been out of action for a week or so, now time to try and round up bits and pieces of all the news I missed…

First up is Solar Storm Watch, which allows data from solar observation probes to be analysed by users of the website. They have announced that through their twitter feed, people will soon be alerted in close to real time when a storm has erupted in our direction, giving some idea of when the best time to look for aurorae, like these, might be. That video involved Stuart Clark, who wrote a book called the Sun Kings, which includes the story of the first observation of a solar flare linked to a resulting auroral storm, one by Richard Carrington in 1859, and who recently recommended ten good easy going books for astronomy enthusiasts.

Secondly, the original Zooniverse project Galaxy Zoo has turned its best known story – the discovery by user Hanny van Arkel of an unusual feature in the zoo data that turned out to be an unusual and very large form of nebula, the origins of which are still contested – into a comic. They have produced promotional cards and will be premiering the comic on the web at 3am on the 4th of September (because Dutch discoveries in a UK based program do need to be premiered in the USA…).